Whole Grains and Health. Группа авторов
Others have also suggested that once more than 10% of the dietary fibre has been removed or disintegrated then the resulting ingredient or product can no longer be considered to be whole grain.(1) However, this is complicated, as total dietary fibre may not reflect the effect of processing that can have a major impact on biological function(7) even if total fibre does not change. For example, some water soluble compounds may be leached out during boiling of cereal products.
Currently, two “user friendly” and accurate ways to report whole grain content are available in different parts of the world, helping researchers, consumers and policy‐makers alike. The first is the QUID labeling used in Europe (see earlier), which clearly documents any whole grains as a percentage of the product as consumed.(1) The second is the Whole Grain Stamp, a labeling certification programme offered through the non‐profit Oldways Whole Grains Council, which displays the grams of whole grain ingredients per serving of more than 13,000 products in 63 countries.
An important additional aspect of quantifying whole grain content is to report the proportion of different grains. As interest in understanding the differential effects of different grains increases, breaking down daily whole grain intake into different types of grain is necessary(8,9): whole grain oats or rye, for instance, may be associated with different health benefits than whole grain wheat or barley. This is usually done with QUID labeling, and is recommended as part of guidelines for whole grain food labeling.(1)
5.2.3 Whole grain contents in different cereal foods
Cereal‐based foods are highly diverse and in most categories of cereal products it is possible to have products that are (or are close to) 100% whole grain. Until the past 150 or so years, most flour produced was whole grain, due to the difficulty of cleanly separating bran and germ from the endosperm. As white flour has become readily available and cheap, it has dominated cereal products for more than a century, and food manufacturers have grown accustomed to the ease of making uniform products, and consumers have adapted to the flavor and texture of refined grains. These habits present challenges for reintroducing a wide range of whole grain foods. In this section, we summarize the range of whole grain content in different cereal food categories, and in Table 5.1, average amounts of whole grains in different food products are presented.
a. Bread
Bread is one of the most common cereal foods, and intake is nearly ubiquitous among all people. Bread as a product is highly diverse, both in terms of ingredients (e.g., wheat, rye, corn/maize, barley, gluten‐free dough mixes) and processing (yeast leavened, sourdough, crispbread and unleavened flatbreads; short or long fermentation; use of enzymes and additives to improve shelf‐life and loaf properties). The whole grain content of bread varies between 0% and 100% of the flour component, with the increasing amount of whole grain in bread usually leading to denser loaf volume. However, the addition of baking improvers such as vital gluten or enzymes can give acceptable volume to breads with 100% or close to 100% whole grain. Some baking enzymes are known to have side activities that break down dietary fibre, which may be a concern as dietary fibre is sometimes used as a reference for whole grains in a product.
Table 5.1 Flour content and potential contribution to whole grain intake of common grain‐based products, based on Marquart et al 2006. Alkylresorcinol content is included to give an idea of how one proposed marker for whole grain reflects the proportion of whole grains in a product. Note that as alkylresorcinols are only present in wheat, rye, barley and quinoa, they do not universally reflect the whole grain content of foods.
Sources: Ross AB, Svelander C, Karlsson G et al. (2017) Identification and quantification of even and odd chained 5‐n alkylresorcinols, branched chain‐alkylresorcinols and methylalkylresorcinols in Quinoa (Chenopodium quinoa). Food Chem 220, 344–351; Chen Y, Ross AB, Åman P et al. (2004) Alkylresorcinols as markers of whole grain wheat and rye in cereal products. JAgricFood Chem 52, 8242–8246; Ross AB (2012) Analysis of alkylresorcinols in cereal grains and products using ultrahigh‐pressure liquid chromatography with fluorescence, ultraviolet, and coulArray electrochemical detection. J Agric Food Chem 60, 8954–8962; Ross AB, Kochhar S (2009) Rapid and sensitive analysis of alkylresorcinols from cereal grains and products using HPLC‐Coularray‐based electrochemical detection. J Agric Food Chem 57, 5187–5193; Andersson AAM, Åman P, Wandel M et al. (2010) Alkylresorcinols in wheat and rye flour and bread. J Food Compost Anal 23, 794–80.
| Product | Flour/grain % | Type of grains | Serving size (fresh weight) | Maximum contribution to whole grain intake per serving (g) | Total alkylresorcinol content (μg/g dry weight) |
|---|---|---|---|---|---|
| Bread | |||||
| White‐wheat bread | 51 | Wheat | 28 | 0 | 20a |
| Whole‐wheat bread | 51 | Wheat | 28 | 14 | 438a |
| Rye bread | 42 | Rye and wheat | 30 | 12 | 412a |
| Breakfast cereal | |||||
| Corn flakes | Corn | 30 | 0 | 0 | |
| Whole wheat/rice flakes | 80 | Wheat and rice | 30 | 24 | 251 |
| Whole‐wheat biscuits | 100 | Wheat | 40 | 40 | 478a |
| Bran‐based cereal | 85 | Wheat bran | 40 | 0 | 1700 |
| Rolled oats/oatmeal (not cooked) | 100 | Oats | 30 | 30 | 0 |
| Main meals | |||||
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Pizza
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